Overhead and roll-up doors have multiple uses, serving primarily as a means for permitting entry into garages, loading docks, trucks, warehouses, recreational and work spaces, or any room or building that must accept entry of large objects, such as vehicles; any object that must be secured by a door that is closed and locked.
For example, in the case of residences, garages are multi-purpose rooms requiring a means permitting and preventing entry. In addition to housing vehicles, garages store household items and quite often serve double-duty as workshops and recreation rooms. While being used for these purposes, garage doors are kept open to let in air and sunlight. However, quite often, traditional overhead or roll-up doors let more than clean air and sunlight in. Unwanted dust, dirt, and insects are often found in garages, having entered through an open garage door. Similar, unwanted intrusion is found in warehouses, loading docks, trucks and other similar kinds of enclosures.
Clearly, a means for permitting desired items and filtering out those that are unwanted becomes a desirable objective for any kind of room or building requiring an overhead or roll-up door. It will be appreciated, for example, that a means for securing a door, yet permitting entry of circulating air, while keeping out dust and dirt will be advantageous. Furthermore such a securing means will permit pets to be kept in an enclosure, which, otherwise, would be too hot and would not permit adequate air to circulate to enclosed animals.